CS260916B1

CS260916B1 - Process for preparing methyl N - (- N '- (3'-methylphenyl) carbamoyloxy) phenyl) carbamate or ethyl N - ((3- (N'-phenyl) carbamoyloxy) phenylcarbamate

Info

Publication number: CS260916B1
Application number: CS854663A
Authority: CS
Inventors: Tomas Sopuch; Jiri Pscheidt; Lubos Sadlo; Jan Laska
Original assignee: Tomas Sopuch; Jiri Pscheidt; Lubos Sadlo; Jan Laska
Priority date: 1985-06-25
Filing date: 1985-06-25
Publication date: 1989-01-12
Also published as: CS466385A1

Abstract

Způsob přípravy látky obecného vzorce I, v němž Rl=Ř2=CH3 nebo Ri=H a R2=ethyl reakcí arylisokyanátu s alkyl-N-(3-hydroxyfenyl) -karbamátem v organickém rozpouštědle. Podstata spočívá v tom, že se do roztoku nebo suspenze alkyl-N-(3-hydroxyfenyl)- -karbamátu dávkuje arylisokyanát ve dvou stupních, a to tak, že se nejprve nadávkuje 10 až 45 % celkové dávky arylisokyanátu najednou nebo minimálně rychlostí 1 % celkové dávky za minutu a následně se dávkuje rovnoměrně během 3 až 5 hodin zbývající množství arylisokyanátu rychlostí 0,07 až 0,5 % celkové dávky za minutu.A method for preparing a substance of general formula I, in which R1=Ø2=CH3 or Ri=H and R2=ethyl by reacting an aryl isocyanate with an alkyl-N-(3-hydroxyphenyl)-carbamate in an organic solvent. The principle consists in dosing the aryl isocyanate into a solution or suspension of the alkyl-N-(3-hydroxyphenyl)-carbamate in two stages, by first dosing 10 to 45% of the total dose of aryl isocyanate at once or at a minimum rate of 1% of the total dose per minute and then dosing the remaining amount of aryl isocyanate evenly over 3 to 5 hours at a rate of 0.07 to 0.5% of the total dose per minute.

Description

260916 2

These substances are most often prepared by reaction of the aryl isocyanate and the alkyl N- (-3-hydroxyphenyl) carbamate and find use under the trade names phenmedipham and desmedipham as effective herbicide preparations for weed control in sugar beet and other crops.

Most preferably, the preparation of the compounds is carried out in solvents such as tetrahydrofuran, dioxane, dimethylformamide at room temperature. For practical use, said solvents are less suitable for economic and hygienic reasons. The dosing of the aryl isocyanate is carried out at once or slowly uniformly, with a reaction time of up to 20 hours. Although a high yield of, for example, up to 96% of theory is achieved, reduced product quality is apparent, for example, from thaws which are 2 to 3 degrees lower than pure substances. Subsequent to recrystallization of the product from another solvent to reduce the yield of the desired product to improve the desired product quality. Reaction of alkyl-N- (3-hydroxyphenyl) carbamate with an aryl isocyanate in inert solvents such as chlorobenzene or toluene at lower temperatures occurs only in the presence of a higher amount of catalyst, preferably up to equimolar to alkyl N- (3-hydroxyphenyl) carbamate . This, however, leads to a reduction in the stability of the desired product in the presence of a larger amount of base and also a very difficult recovery of the catalyst used. When a catalyst of, for example, triethylamine (0.5 to 5%) is used for alkyl-N- (3-hydroxyphenyl) carbamate, the reaction occurs at temperatures as low as 50 ° C. A higher temperature than 85 ° C is unsuitable for the reaction because of the irreversible deposit of the desired product on the alkyl N- (3-hydroxyphenyl) carbamate and the unstable N- (3-hydroxyphenyl) carbamate, which form as by-products derivatives sym. N, N'-bis- (aryl) -urea. When carrying out the reaction of alkyl-N- (3-hydroxyphenyl) carbamate with an aryl isocyanate after catalysis of triethylamine in an amount of about 0.5 to 5% to alkyl-N- (3-hydroxyphenyl) carbamate at 50 to 80 ° C, the aryl isocyanate is rapidly to suddenly expel the product and to completely solidify the reaction mixture. The poorly agitated reaction mixture is formed at a slow even dosage of the aryl isocyanate, resulting in imperfect reacting of the reactants. Although the reaction mixture is partially improved during the further agitation at the indicated stirrer temperature, the isolated products contain an increased content of side-reactions, in particular alkyl-N- (3-hydroxyphenyl) carbamate in an amount of up to 2% and sym. N, Ν'-bis- (aryl) -

carbamate by reaction of the aryl isocyanate with alkyl N- (3-hydroxyphenyl) carbamate by catalysis with triethyl amine at a temperature of 50 to 80 ° C by feeding the aryl isocyanate or its solution in an organic solvent to a solution or suspension of alkyl-N- (3-hydroxyphenyl) carbamate also in the organic solvent. The invention is based on the fact that the dosing is carried out in two steps, by first dispensing 10 to 45% of the total dose of aryl isocyanate at one time or at a minimum of 1% of the total dose per minute, and subsequently dosing the remaining amount of aryl isocyanate evenly at a rate of 0.07. up to 0.5% of the total dose per minute. The optimum dosing rate of the aryl isocyanate in the second step is about 0.1 to 0.25 and the total dose of aryl isocyanate per minute. In the case of the invention, a uniformly shedding of the product in a highly stirrable form occurs during the dosing of the second part of the aryl isocyanate. Due to the very good reactivity of the reactants, the products contain a very low content of by-products in the amount of below 0.4%, in most cases below 0.1% up to hundredths of a percent, while at the same time obtaining a very high reaction rate. Exemplary embodiments are set forth to illustrate the invention. Example 1

After the addition of 8 g of triethylamine to the dehydrated solution of 595 g of methyl N- (3-hydroxyphenyl) carbamate in chlorobenzene, 1 200 g of reaction 3 260916 chlorobenzene solution of m-tolyl isocyanate containing 156 g of 100% m were added to the contents of the flask within 20 minutes. -tolyl isocyanate. After washing the reaction mixture, a second portion of the reaction chlorobenzene solution of m-tolyl isocyanate in an amount of 2,446 g containing 318 g of 100% m-tolyl isocyanate was metered evenly over the next 5 hours. The feed rate of m-tolyl isocyanate in stage 1 was 1.65% of the total dose of tolylisocyanate per minute and the rate of m-tolyl isocyanate in stage 2 was 0.22% of the total dose of m-tolyl isocyanate per minute. The temperature of the reaction mixture was maintained at 70-75 ° C during m-tolyl isocyanate dosing. The first crystals of the product dropped after 40% of the theoretical dose of m-tolyl isocyanate. During the addition of m-tolyl isocyanate, the reaction mixture was very well stirrable. After charging the m-tolyl isocyanate, the reaction mixture was stirred for an additional 2 hours at 70-75 ° C and subsequently cooled to 0 ° C over 3 hours. The product was isolated on a laboratory centrifuge and washed with 250 g of chlorobenzene cooled to 5 ° C. The product was dried at 20-75 ° C and 0.000 1 MPa pressure. 1,028 g of methyl N- (3-N '- (31-methylphenyl) carbamoyloxy-4-phenyl-4-carbamate were obtained, i.e. in the yield 96.2% of theory. The content of methyl N - (3-hydroxyphenyl) carbamate 0.1% and the content of sym. N, N 1 -bis- (m-tolyl) -urea 0.04%.

The melting point of the product was 143-144 ° C. Example 2 Preparation of methyl N- [3- [N '- (3'-methylphenyl) carbamoyloxy] phenyl] carbamate.

The procedure was analogous to Example 1 except that the chlorobenzene solution of m-tolyl isocyanate was used, which was prepared by dissolving 474 g of m-tolyl isocyanate in 3600 g of anhydrous chlorobenzene. The rate of m-tolyl isocyanate in step 1 was 1.65% of the total m-tolyl isocyanate per minute and the m-tolyl isocyanate feed rate in step 2 was 0.22% of the total m-tolyl isocyanate per minute. 1031 g of methyl N- [N '- (3' - methylphenyl) carbamoyl] -4-phenyl-carbamate were obtained, i.e. in a yield of 96.5% of theory. Methyl N- (3-hydroxyphenyl) carbamate content of 0.11% and the content of sym. N, Ν-bis- (m-tolyl) -urea 0.09%. The melting point of the product was 143-144 ° C. Example 3 To a solution of methyl N- (3-hydroxyphenyl) carbamate in toluene prepared by dissolving 400 g of methyl N- (3-hydroxyphenyl) carbamate in 2800 g of toluene was added 10 g of triethylamine and subsequently dosed in 5 minutes 35 g of 100% m-tolyl isocyanate. 248 g of 100% m-tolyl isocyanate were metered evenly at 50-65 ° C over the next 15 hours. The dosing rate of m-tolyl isocyanate in stage 1 was 2.47% of the total dose of tolylisocyanate per minute and the rate of dosing in stage 2 was 0.097% of the total dose of tolylisocyanate per minute. After charging the m-tolyl isocyanate, the reaction mixture was stirred at 60 ° C for 1 hour and the product was isolated after cooling to-0 ° C. Yield: 679 g of methyl N- [3- (3 ') - (3'-methylphenyl) carbamoyloxy] -4-phenyl] -carbamate in a yield of 94.5% of theory. The liquid chromatographic content of the product was determined to be 0.006% methyl N- (3-hydroxyphenyl) carbamate and the content of sym. N, N'-bis- (m-tolyl) -urea 0.36%. Melting point: 143-144 ° C. <Example 4

The procedure was similar to that of Example 1 except that the reaction was carried out at a temperature of 80-85 ° C and the dosing time of 2 part of the chlorobenzone solution of aryl isocyanate was 3 hours. The temperature of the reaction mixture was 75-80 ° C. The feed rate of m-tolyl isocyanate in the second stage was 0.37% of the total dose of m-tolyl isocyanate per minute. 1 020 g of methyl N- (3- [n '- (3-l-methylphenyl) carbamoyloxy) -phenyl] -carbamate were obtained in 95.45% yield. Methyl-N- (hydroxyphenyl) content was determined by liquid chromatography. ) carbamate 0.03% and content sym. N, Ν-bis- (m-tolyl) -urea 0.02%. The melting point of the product was 142-143 ° C. EXAMPLE 5 Preparation of Methyl N- [3- (1H-methyl-phenyl) -carbamoyloxy] -phenylcarbamate. κ a dehydrated solution of methyl N- (3-hydroxyphenyl) carbamate containing 500 g of methyl N- (3-hydroxyphenyl) carbamate and 1800 g of p-xylene was charged with 3.0 g of triethylamine after cooling to 70 ° C; subsequently, 300 g of a reaction solution of m-tolyl isocyanate in p-xylene containing 119 g of 100% substance were metered in over 50 minutes. During the next 6 hours, a second portion of the reaction solution of m-tolyl isocyanate in p-xylene, i.e. 529.4 g of a solution containing 210 g of 100% substance, was dispensed evenly at a temperature of 70-75 ° C. The 1st dose was dosed within 5 minutes, the m-tolyl isocyanate dosing rate in stage 1 was therefore 7.2% of the m-tolyl isocyanate total dose per minute and the m-tolyl isocyanate dosing rate in stage 2 was 0.177% of the total m-tolyl isocyanate dose per minute . The reaction mixture was stirred for an additional 5 hours at 70-75 ° C and the temperature was evenly cooled to 5 ° C over the next 7 hours. After isolation, 861.5 g of methyl N- (4-N, N '- (3'-methylphenyl) carbamoyloxy) phenyl-carbamate were obtained in a yield of 95.9% of theory. The melting point of the product was 143-144 ° C. Example 6

In a reaction flask equipped with a wheel stirrer, 1 200 g of chlorobenzene and 600 g of ethyl N- (3-hydroxyphenyl) carbamate were introduced. After heating the contents of the flask to 65 ° C and adding 7.5 g of triethylamine, 670 g of a chlorobenzene solution of phenylisocyanate containing 80 g of 100% phenylisocyanate were added to the flask over a period of 20 minutes and uniformly at a temperature of 65 to 80 ° C over the next 5 hours. 70 DEG C., the remaining amount of the phenylisocyanate solution, i.e. 2680 g of solution containing 320 g of 100% phenyl isocyanate, is fed. The dosing time of the 1 part phenyl isocyanate was incorrectly reported. Thus, the actual dosing time was 20 minutes. The rate of phenylisocyanate dosing in stage 1 was therefore 1.0% of the total batch of phenyl isocyanate per minute and in the second stage 0.22% of the total phenylisocyanate dose per minute. After stirring and cooling the reaction mixture to 3 ° C, the product was isolated. 82 928 g of crystalline ethyl N - (N 1 -phenyl) carbamoyloxy-4-phenyl} carbamate were obtained, i.e. 93.4% of theory. Ethal-N- (3-hydroxyphenyl) content was determined in the product by liquid chromatography. ) carbamate 0.15% and sym. N, N'-diphenyltin 0.035%. Melting point 119-121 ° C. Example 7 To 750 g of methyl N- (3-hydroxyphenyl) carbamate and 1700 g of chlorobenzene were added 10 g of triethylamine and the contents of the stirred flask were heated to 70 ° C. Then, 100 g of a solution of m-tolyl isocyanate in chlorobenzene containing 270 g of m-tolyl isocyanate were metered in at a time. An additional 1 345 g of a solution of m-tolyl isocyanate in chlorobenzene containing 335.5 g of m-tolyl isocyanate, i.e. at a rate of 0.15% of the total dose of m-tolyl isocyanate per minute, was metered into the contents of the stirred flask over the next 6 hours. During the addition of tolyl isocyanate, the reaction mixture was very well stirrable. After charging the m-tolyl isocyanate, the reaction mixture was also stirred at 70 ° C for 5 hours and then uniformly cooled to 0 ° C. After isolation and drying of the product, 1 305 g of product was obtained, i.e. in a yield of 96.9% of theory. Liquid chromatography determined the product content of 99.5%, methyl N- (3-hydroxyphenyl) carbamate content of 0.05%, sym. N, Ν-bis- (m-tolyl) -urea 0.1%. The product temperature was 143-144 ° C. Example 8- known procedure

The procedure was the same as in Example 7 except that m-tolyl isocyanate was metered in over 30 minutes. After two hours of stirring the reaction mixture, the product was suddenly precipitated and an unmixed reaction mixture was formed and the reaction mixture solidified.

Claims

EXAMPLE 9 Known Procedure The procedure was the same as in Example 7 except that m-tolyl isocyanate was dosed evenly for 6 hours. After dosing about 60% of the m-tolyl isocyanate dose, the product was suddenly precipitated and the reaction mixture was partially solidified. The reaction mixture was still very thick and difficult to stir for several hours. After charging the m-tolyl isocyanate, the reaction mixture was stirred at 70 ° C for a further 6 hours. Further uptake was as in Example 7. 1 223 g of product was obtained, ie. in a yield of 90.8% of theory. Liquid chromatography determined the product content of 96.1%, methyl N- (3-hydroxyphenyl) carbamate content 1.2%, and symmetry content. N, N'-bis- (m-tolyl) -urea2.5%. Melting point 138-142 ° C. SUBJECT MATTER

with alkyl N- (3-hydroxyphenyl) carbamate under the catalysis of triethylamine at a temperature of 50 to 80 ° C by feeding the aryl isocyanate or a solution thereof in an organic solvent to a solution or. also suspending alkyl N- (3-hydroxyphenyl) carbamate also in an organic solvent characterized in that the dosing is carried out in two steps by first dispensing 10 to 45% of the total amount of aryl isocyanate at a rate of at least 1% of the total dose per minute and subsequently the remaining amount of aryl isocyanate is metered uniformly over a period of 3 to 15 hours at a rate of 0.07 to 0.5 and the total dose per minute.